It is generally known that, with a hybrid drive for a motor vehicle, a phase shifter gearbox (i.e., a gear arrangement that permits superimposition of torque from the engine and electric machine) formed in a planetary design can be used for the superimposition of the torques and rotational speeds of an internal combustion engine and an electric machine. Compared to other types of phase shifter gearboxes, a planetary transmission has the advantage of compact dimensions and balanced bearing loads of the transmission components.
DE 199 34 696 A1 describes a combination of an internal combustion engine, an electric machine and a phase shifter gearbox designated as an electrodynamic drive system (EDA), which is upstream of a manual transmission carried out in a lay-shaft design and enables wear-free start-up. In a first embodiment of this hybrid drive according to FIG. 1 therein, the phase shifter gearbox is formed as a simple planetary transmission with one sun gear, one planetary carrier supporting several planetary gears and one ring gear. The ring gear of the planetary transmission is connected in a torque-proof manner to the drive shaft of the internal combustion engine and forms the first input element of the phase shifter gearbox. The sun gear of the planetary transmission is connected in a torque-proof manner to the rotor of the electric machine and forms the second input element of the phase shifter gearbox. The planetary carrier of the planetary transmission is connected in a torque-proof manner to the input shaft of the manual transmission and forms the output element of the phase shifter gearbox.
With this hybrid drive, the wear-free start-up takes place by the fact that, with a largely constant rotational speed of the internal combustion engine, the electric machine is initially controlled in generator mode with increasing drag torque until it reaches the rotor standstill, and is then accelerated during engine mode with a reverse direction of rotation until reaching the synchronization of the transmission components of the planetary transmission. Upon reaching the synchronization in the planetary transmission, a lock-up clutch arranged between the sun gear and the planetary carrier is closed, such that, in the further course of the internal combustion engine driving mode, the planetary transmission revolves as a unit. In this operating state, the electric machine can be operated as a motor for a boost operation, operated as a generator for the charging of an electric energy storage device, or switched to powerless. If the drive shaft of the internal combustion engine is connected to the ring gear of the planetary transmission through a separating clutch that can be engaged and disengaged, the internal combustion engine can also be decoupled and stopped in order to enable pure electric driving mode. The manual transmission of this hybrid drive can be used, without any change, for a conventional drive, with which the start-up with the internal combustion engine takes place, subject to wear, through the slip operation of a separating clutch formed as a friction clutch.
Arrangements of an internal combustion engine, an electric machine and a phase shifter gearbox that are similar in structure and function and are likewise allocated to a manual transmission are known from U.S. Pat. No. 5,839,533 A and DE 10 2004 005 349 A1.
In contrast to the aforementioned hybrid drives, DE 10 2007 042 949 A1 describes a hybrid drive, with which an arrangement of an internal combustion engine, an electric machine and a phase shifter gearbox is upstream in terms of drive technology of a manual transmission carried out in a lay-shaft design with two input shafts and a common output shaft. The phase shifter gearbox is in turn formed as a simple planetary transmission. The ring gear of the planetary transmission is connected in a torque-proof manner to the first input shaft of the manual transmission, which is connected on the input side to the drive shaft of the internal combustion engine through a separating clutch formed as a friction clutch and is brought into drive connection within the manual transmission to the output shaft of the manual transmission selectively through a first group of shiftable spur gear stages. Thus, the ring gear of the planetary transmission forms the first input element of the phase shifter gearbox. The sun gear of the planetary transmission is connected in a torque-proof manner to the rotor of the electric machine and therefore forms the second input element of the phase shifter gearbox. The planetary carrier of the planetary transmission is connected in a torque-proof manner to the second input shaft of the manual transmission, which is formed as a hollow shaft, is arranged coaxially through the first input shaft, and is brought into drive connection, within the transmission, with the output shaft of the manual transmission selectively through a second group of shiftable spur gear stages. Accordingly, the planetary carrier of the planetary transmission forms the output element of the phase shifter gearbox.
With this hybrid drive, the start-up can be carried out free of wear with a shifted spur gear stage of the second group as with hybrid drives described above. In normal driving mode, the two input shafts are connected to each other in a torque-proof manner through a coupling shift element, by which the planetary transmission is blocked in itself, thus revolves in the block. With such hybrid drive, it is also possible to, upon a gearshift between two spur gear stages of both groups, synchronize the shifting clutch of the spur gear stage of the target gear with an open coupling shift element by means of the electric machine. Such a manual transmission can be derived from a dual-clutch transmission, with which, instead of the electric machine and the phase shifter gearbox, a second separating clutch formed as a friction clutch is provided, through which the second input shaft is connectable to the drive shaft of the internal combustion engine.
Arrangements of an internal combustion engine, an electric machine and a phase shifter gearbox that are similar in structure and function and are upstream in terms of drive technology of a manual transmission with two input shafts and one output shaft are also known from U.S. Pat. No. 6,645,105 B2 and DE 10 2006 059 591 A1.
In contrast to the aforementioned hybrid drives, DE 10 2010 030 567 A1 and DE 10 2010 043 354 A1 describe hybrid drives with which a manual transmission formed in a lay-shaft design, which is combined with a phase shifter gearbox formed in a planetary design for the linkage of an electric machine in terms of drive technology, is specifically designed for use in a hybrid drive.
In a first embodiment of the hybrid drive of DE 10 2010 030 567 A1 according to FIG. 1 therein, the two input shafts are arranged in a manner coaxially and axially adjacent to each other, and are connectable to each other in a torque-proof manner through a coupling shift element. The first input shaft is connectable to the drive shaft of the internal combustion engine through a separating clutch formed as a friction clutch and can be brought into drive connection with the output shaft through a shiftable spur gear stage. The phase shifter gearbox formed as a simple planetary transmission is arranged in a manner coaxially and axially adjacent to the second input shaft. The ring gear of such planetary transmission is connected in a torque-proof manner to the second input shaft of the manual transmission, which is connectable in a torque-proof manner to the first input shaft through a coupling shift element and can be brought into drive connection with the output shaft through a shiftable spur gear stage. Thus, the ring gear of the planetary transmission forms the first input element of the phase shifter gearbox. The sun gear of the planetary transmission is connected in a torque-proof manner to the rotor of the electric machine and therefore forms the second input element of the phase shifter gearbox. The planetary carrier of the planetary transmission is connectable in a torque-proof manner to the second input shaft of the manual transmission through a bypass shift element and can be brought into drive connection with the output shaft through an additional shiftable spur gear stage. Accordingly, the planetary carrier of the planetary transmission forms the output element of the phase shifter gearbox.
Such known hybrid drive features, in addition to the possibility of wear-free start-up, three gears for the internal combustion engine driving mode and two gears for the electromotive driving mode. It is also possible to charge an electric energy storage device by means of the internal combustion engine and to start a motor of the internal combustion engine by means of the electric machine. The small number of gear steps available in the internal combustion engine driving mode and, based on the drag losses of the spur gear stages, the low transmission efficiency in the electric driving mode can be specified as disadvantages of such hybrid drive.
With the hybrid drive according to DE 10 2010 043 354 A1, a phase shifter gearbox formed as a simple planetary transmission is arranged inside the manual transmission carried out in a lay-shaft design that features two input shafts and one output shaft. The first input shaft of the manual transmission is arranged in a manner axially parallel to the output shaft, is connected to the drive shaft of the internal combustion engine through a separating clutch formed as a friction clutch, and can be brought into drive connection with the output shaft of the manual transmission through two spur gear stages consisting only of idler gears. The second input shaft of the manual transmission is arranged in a manner axially parallel to the first input shaft and the output shaft, is connected in a torque-proof manner to the rotor of an electric machine, and can likewise be brought into drive connection with the output shaft of the manual transmission through two spur gear stages consisting only of idler gears. The spur gear stage of the first input shaft and the second input shaft are arranged in identical or nearly identical gear levels, and in one case use a common idler gear that is arranged on the output shaft. In another case, the idler gears of the two spur gear stages that are arranged on the output shaft are connected to each other in a torque-proof manner. The phase shifter gearbox formed as a simple planetary transmission is arranged between the two gear levels, coaxially on the output shaft. The ring gear of the planetary transmission is connected in a torque-proof manner to the two idler gears of the first gear level that are connected to each other in a torque-proof manner, can be brought into drive connection with the first input shaft or the second input shaft through a shift element, and is connectable in a torque-proof manner to the output shaft through an additional shift element. Thus, the ring gear can form the first input element or the second input element of the phase shifter gearbox. The sun gear of the planetary transmission is connectable in a torque-proof manner with the common idler gear of the second gear level through a shift element, can be brought into drive connection with the first input shaft or the second input shaft through a shift element, and is directly connectable in a torque-proof manner with the output shaft through an additional shift element. Therefore, the sun gear of the planetary transmission can likewise form the first input element or the second input element of the phase shifter gearbox. The planetary carrier is connected in a torque-proof manner to the output shaft and accordingly forms the output element of the phase shifter gearbox.
This known hybrid drive features, in addition to the option of wear-free driving, seven gears for the internal combustion engine driving mode, including four winding-path gears, and seven gears for the electromotive driving mode, including four winding-path gears. Moreover, with this hybrid drive, is possible to charge an electrical energy storage device through the internal combustion engine and start the motor of the internal combustion engine through the electric machine. However, disadvantages with such hybrid drive include the high total number of required shift elements, the large number of shift elements to be engaged and disengaged for most gears, and the poor transmission efficiency in the winding-path gears.